Hi Tom: You’re absolutely right about man’s effect on the planet for as long as we’ve walked upright. I’m sorry that we may have overstated our case in suggesting that mankind walked lightly on the Earth prior to the Industrial Revolution. Yes, prior to 1850 we decimated forests, hunted animals to extinction and altered the Earth in many ways but never brought our own species anywhere near the brink of extinction. An interesting side note about animal extinction, we’re currently losing about one species per hour due to their inability to adapt to the warming climate. The rate is increasing as the Earth warms and habitats disappear.

We do know that many indigenous people lived far more sustainably than “advanced civilizations.” However, our intent was to point out the extraordinary change that occurred after the mid 1800s. That rapid change had everything to do with the ever greater amounts of energy use by the developing and developed world – fueled by the burning of coal, oil and gas. And that, scientists worldwide state, is the basis of what is becoming runaway climate change.